This invention relates to an airbag module that selectively diverts inflation gas away from an airbag.
Airbag modules typically comprise an airbag and an airbag inflator. When triggered by a crash detection system, the airbag inflator rapidly generates an inflation gas through a chemical or other reaction to inflate the airbag. The inflated airbag serves as a cushion against injury for a vehicle occupant.
The location of the vehicle occupant with respect to the airbag may affect the effectiveness of the airbag as a cushion. If the vehicle occupant is too close to the airbag, the full inflation of the airbag may result in less than optimal cushioning of any impact. Accordingly, it is desirable to inflate the airbag to less than full capacity when the vehicle occupant is too close to the airbag.
Systems exist that detect the location of the vehicle occupant. When these systems sense that the vehicle occupant is too close to the airbag, the airbag is inflated to less than full capacity. A dual-stage inflator serves to inflate the airbag in this way. The inflator's first stage partially inflates the airbag, and when the second stage triggered in addition it inflates the airbag to a maximum level.
However, a dual-stage inflator is generally more expensive than a single-stage inflator. Moreover, these inflators only inflate the airbag to two different levels: a high output level is provided when both stages are utilized, and a low output level is provided by only the primary stage. Having only two different inflation levels for the airbag may not adequately accommodate the multiple positions of the vehicle occupant during a crash. For example, the vehicle occupant may be too close to the airbag during deployment to expand the airbag with the high output, but yet be too far away from the airbag for a low output level inflation. The invention taught herein will allow for virtually any level of airbag inflation.
In addition to altering the inflation level of the airbag due to vehicle occupant position, it may be desirable to inflate the airbag to more than two different levels under different circumstances. For example, the weight of the vehicle occupant affects the level of inflation in a crash because a heavier vehicle occupant requires more cushioning than a lighter vehicle occupant. Also, different levels of crash severity may necessitate a greater range of inflation levels.
A need therefore exists for a simple and inexpensive airbag module that permits an airbag to be inflated to a greater variety of inflation levels.